Developments in or relating to hand drying

ABSTRACT

A fixture fits next to the basin of a sink. The fixture has a water spout arranged to project over the basin of the sink. The water spout has a water nozzle arranged for connection through the spout to a water supply. The fixture further includes an elongate air-knife discharge outlet for discharging an air-knife onto a user&#39;s hand to dry it. This discharge outlet is arranged for connection to an air supply via an air duct, the air duct having a side wall extending between a first end of the duct and a second end of the duct. The first end of the duct is connected to the air supply, the second end of the duct forms—or is connected to—the air-knife discharge outlet. The outlet extends across the second end of the duct, as opposed to being provided in the sidewall of the duct.

REFERENCE TO RELATED APPLICATIONS

This application is a national stage application under 35 USC 371 of International Application No. PCT/GB2012/051370, filed Jun. 14, 2012, the entire contents of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates generally to the field of hand drying, and in particular to arrangements which use an air-knife to dry the hands.

BACKGROUND OF THE INVENTION

In commercial washrooms, it is common to provide one or more sinks or water basins for washing, and one or more separate, wall-mounted hand-dryers which users can then use to dry their hands.

There are three distinct types of hand dryer on the market: “warm-air” hand dryers, “high speed” hand dryers and “air-knife” hand dryers.

Warm air hand dryers are very well known. They are invariably low flow, low speed machines which rely on heating the air to promote an evaporative drying effect at the surface of the hand. Examples include the Model A Series of hand dryers manufactured and marketed by World Dryer Corporation. The heated airflow is typically discharged through a single nozzle and the drying action is a “hand-over-hand” action, requiring the user to rub the hands together under the nozzle with the aim of encouraging the evaporative drying effect.

High speed hand dryers, as the name suggests, use high speed airflow (>80 m/s) to provide a momentum-drying effect at the surface of the hands. Examples include the Xlerator® hand dryer manufactured and marketed by Excel Dryer Inc. Again the airflow is typically discharged through a single relatively large nozzle and the mode of use is somewhat similar to the “hand-over-hand” action of the warm air dryer, with the hands being held or cupped together underneath the nozzle to dry them. However, instead of being evaporated, the vast majority of the water on the surface of the hands is instead driven or blasted from the hands by the high-momentum airflow, with evaporation accounting for only a small proportion of water removal. The airflow tends not to be heated, though waste heat from the motor may in some cases be used to heat the airflow to a degree.

The third general type of hand dryer is the air-knife hand dryer, examples of which include the Dyson Airblade range of Hand Dryers manufactured by Dyson (UK) Limited and the Jet Towel hand dryer manufactured by Mitsubishi Electric Corporation.

These hand dryers use an air-knife—a sheet or curtain of moving air—to remove the water from the user's hands. The mode of operation is analogous to the established use of air knives in industry to remove debris or liquid from the surface of a product (see e.g. EP2394123A1, which describes removal of debris from a glass sheet using air knives): the air-knife moves across the surface of the hand and, as it does so, wipes or scrapes the water from the surface of the hand.

In both the Dyson Airblade and the Mitsubishi Jet Towel, two opposing, stationary air-knives are used, one for each side of the user's hand. The hands are inserted between the air-knives and then withdrawn slowly to effect the required relative movement between the hands and the air knives.

In the Dyson arrangement—shown in FIG. 1—the air knives are discharged through narrow, continuous slots (only the rear slot a is visible in FIG. 1), each less than 1 mm wide. In the Mitsubishi arrangement—shown in FIG. 2—the air-knife is instead discharged through opposing rows of individual discharge apertures (only the rear row b is visible in FIG. 2): here, the individual jets combine to produce the air knife downstream of the discharge apertures. In each case, the air knife is discharged at high speed (>80 m/s) to provide for an efficient wiping action across the surface of the hand.

SUMMARY OF THE INVENTION

The present invention is concerned with air-knife hand dryers.

According to the present invention, there is provided a fixture for fitting next to the basin of a sink, the fixture comprising a water spout arranged to project over the basin of the sink, the water spout having a water nozzle arranged for connection through the spout to a water supply, the fixture further comprising an elongate air-knife discharge outlet for discharging an air-knife onto a user's hand to dry it, the discharge outlet being arranged for connection to an air supply via an air duct, the air duct having a side wall extending between a first end of the duct and a second end of the duct, the first end of the duct connecting to the air supply, the second end of the duct forming—or being connected to—the air-knife discharge outlet, which outlet extends across the second end of the duct.

One of the problems identified with air-knife dryers is that of managing the disposal of waste water. This is a particular problem for air-knife dryers because the nature of the air-knife drying mechanism means that the water removal is non-evaporative: instead, the water is driven from the hands by the relatively high momentum of the airflow. In the conventional air-knife dryer arrangements described above, the waste water removed from the hands may be collected in a drip tray—which must periodically be emptied—or else is not collected at all and instead simply allowed to evaporate from surfaces on and around the dryer. Neither scheme is particularly hygienic.

The invention advantageously makes use of the existing mains drainage system to manage the waste water more effectively: by incorporating the air-knife dryer on a fixture for a sink so that water driven from the hands can simply drain to mains through the standard drain-hole in the basin of the sink.

The air-knife discharge outlet is not provided in a sidewall of the air duct. Instead, the air-knife discharge outlet extends across the second end of the air duct. This offers a simple air-feed configuration, in which the air is fed axially along the air duct in generally parallel alignment with the principal exit direction of the air-knife. This means that the fixture can be positioned at the back of the basin of the sink the commonplace position for sink fixtures—to direct the air-knife forwardly towards the user. This is achieved without having to turn the airflow inside the fixture, which would introduce losses and create noise.

Each air-knife outlet may comprise an elongate discharge aperture or elongate line of discharge apertures. For example, each air-knife outlet comprises an elongate air slot or plurality of elongate air slots.

The slot, or air slots, may be less than 2 mm wide, intended to provide a laminar, well-defined air knife with minimal wind shear.

The elongate air-knife outlet(s) may be at least 80 mm long, intended to span the width of a typical user's hand. A preferred range of lengths is 110 mm to 150 mm

In one embodiment, the fixture comprises two elongate air-knife discharge outlets—one for each hand. In this case, the discharge outlets may be arranged to extend laterally either side of the water nozzle.

BRIEF DESCRIPTION OF DRAWINGS

Embodiments of the invention will now be described, with reference to the accompanying drawings, in which:

FIGS. 1 and 2 are simplified perspective views of conventional air-knife hand dryers;

FIG. 3 is a perspective view of an arrangement comprising a fixture in accordance with the present invention;

FIG. 4 is sectional view through the fixture shown in FIG. 3;

FIG. 5 is a plan view of the arrangement in FIG. 3;

FIG. 6 is a view from the front of the fixture shown in FIGS. 3 to 5, illustrating the fixture in use; and

FIG. 7 is a simplified perspective view of an arrangement comprising a wall-mounted fixture in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 3-5 show an arrangement comprising a fixture 1 in combination with a sink 3.

The sink 3 may itself be conventional. A “Belfast-type” sink is shown, though other types of sink may alternatively be used. The sink 3 has a standard drain-hole 3 a, in this case positioned towards the rear wall of the basin 3 b of the sink 3 (FIG. 4).

The fixture 1 is fitted next to the basin 3 b of the sink 3 using a locknut 5 underneath the sink 3 which engages with an externally threaded, hollow fixing stud 7 to clamp the fixture 1 in place (the fixture 1 may alternatively be fitted adjacent the sink rather than to the sink itself, according to the style of sink).

The fixture 1 comprises a hollow, curved spout 9 which projects out over the basin 3 b of the sink 3. The spout 9 has a rectangular cross-section, defined by opposing pairs of side walls 9 a, 9 b.

The inside of the spout 9 forms an air duct 11, shown in FIG. 4. This air duct 11 has a first end 11 a and a second end 11 b.

The air duct 11 is connected at the first end 11 a to the hollow fixing stud 7.

The second end 11 b, being the end positioned over the sink basin 3 b in use, is provided with two air-knife discharge outlets: a left-hand air-knife discharge outlet 13 and a right-hand air-knife discharge outlet 15.

The air-knife discharge outlets 13, 15 extend laterally across the second end 11 b of the air duct 11. Each air-knife discharge outlet 13, 15 takes the form of an elongate narrow air slot, less than 2 mm in width—intended to provide a narrow, well-defined air-knife, and more than 80 mm in length—intended to span the width of a typical user's hand.

The hollow fixing stud 7 is connected to a motor-driven fan 17 via a flexible hose 19. The fan 17 is configured in use to drive airflow in through the air duct 11—via the hose 19 and hollow fixing stud 7—and out through the air-knife discharge outlets 13, 15 at a speed in excess of 80 m/s. The airflow is thus discharged from the outlets in the form of two high-speed air-knives.

A water nozzle 21 is provided on the fixture 1, positioned in between the two air-knife discharge outlets 13, 15 so that the outlets extend laterally either side of the central water nozzle 21. The water nozzle 21 connects to the mains water supply line via a flexible pipe 23 which runs through the inside of the air duct 11 and out through the hollow fixing stud 7 (adequate provision will need to be made to route this pipe externally of the air supply line—or alternatively the flexible water pipe may run externally of the air supply line altogether).

On demand, water is delivered through the water nozzle 21 for washing. The fixture 1 is configured for “hands-free” operation to supply the water, using a conventional sensor and control loop which automatically opens a stop valve in the supply line, in response to detection of a user's hands in a washing position. Alternatively, the fixture 1 may be configured for manual operation to supply water.

On demand, air-knives 13 a, 15 a are ejected through the air-knife outlets 13, 15 to dry the user's hands. Again, this is achieved via a conventional sensor and control loop, which automatically switches on the fan 17 in response to detection of a user's hands in a drying position (which should be distinguishable from the aforementioned washing position—which automatically activates the water supply). Alternatively, the fixture may be configured for manual operation.

To commence the hand-drying operation, a user presents his (or her) wet left-hand—palm open—in front of the left-hand air-knife discharge outlet 13 and similarly presents his wet right hand—palm open—in front of the right-hand air-knife outlet 15 on the right hand of the spout 9. The sensor and control loop then operates to activate the fan 17, which forces air under high pressure through the air-knife outlets 13, 15: directing two high-momentum air-knives forwards onto the user's hands. The hands are dried one side at a time: first, the user passes his hands lengthwise up and down in front of the air-knife outlets 13, 15 with the back of the hand facing the air-knife outlets (referred to below as the “standard pass”— illustrated in FIG. 6). Then—after turning over the hands—the user passes his (or her) hands lengthwise up and down in front of the air-knife outlets 13, 15 with the palms facing the air-knife outlets (referred to below as the “reverse pass”).

The “standard pass” and “reverse pass” may each be repeated, as required, and carried out in any order.

FIG. 7 shows an alternative arrangement in which the fixture 10 is wall-mounted above the sink 3, rather than being fitted next to the basin 3 b of the sink 2. In this case a relatively narrow, tubular spout 90 forms the air duct 110 connecting the fan to the air-knife discharge outlets (not visible: on the underside of the spout 90), and the outlets are provided extending across a flared forward end 110 a of the air duct 110. Two outlets are provided, which deliver respective air-knives 130 a and 150 a. Again, the water nozzle (not visible on the underside of the spout 90) is provided between the air-knife discharge outlets to deliver a stream of water 210 a, via a flexible pipe 230 running inside the air duct 110.

The use of air-slots is not essential. The air knife discharge outlets may be formed from a line of air-holes or individual, shorter air slots—similar to the Mitsibishi scheme shown in FIG. 2.

A single, elongate air-knife discharge outlet may instead be provided on the fixture—either with the intention that the user dries one hand at a time, in which case the outlet should preferably be more than 80 mm long, or with the intention that the outlet spans the width of both hands together—in which case the outlet should preferably be more than 150 mm long. 

1. A fixture for fitting next to the basin of a sink, the fixture comprising a water spout arranged to project over the basin of the sink, the water spout having a water nozzle arranged for connection through the spout to a water supply, the fixture further comprising an elongate air-knife discharge outlet for discharging an air-knife onto a user's hand to dry it, the discharge outlet being arranged for connection to an air supply via an air duct, the air duct having a side wall extending between a first end of the duct and a second end of the duct, the first end of the duct connecting to the air supply, the second end of the duct forming—or being connected to—the air-knife discharge outlet, the air-knife discharge outlet extending across the second end of the duct.
 2. The fixture of claim 1, wherein each air-knife discharge outlet comprises an elongate discharge aperture or elongate line of discharge apertures.
 3. The fixture arrangement of claim 1, wherein the air-knife discharge outlet comprises an elongate air slot or plurality of elongate air slots.
 4. The fixture of claim 3, wherein in which the width of the slot(s) is less than 2 mm.
 5. The fixture of claim 1, wherein the air-knife discharge outlet aperture is at least 80 mm long.
 6. The fixture of claim 1, comprising two elongate air-knife discharge outlets.
 7. The fixture of claim 6, wherein the two air-knife discharge outlets are arranged to extend laterally either side of the water nozzle.
 8. An arrangement comprising the fixture of claim 2, the fixture being fitted next to the basin of a sink, the water nozzle being connected to a water supply, the discharge aperture(s) being connected to an air supply arranged for driving airflow through the discharge aperture(s) at an exit velocity in excess of 80 m/s. 